Patent GB-501712-A (GB)
Title: Improvements in and relating to electric lamps and methods of manufacturing the same
IPC: H01K3/20
Filed: 1938-06-20
Abstract: 501,712. Photo-electric apparatus for centring lamp bulbs; valve relays. BRITISH THOMSON-HOUSTON CO., Ltd. June 20, 1938, No. 18284. Convention date, June 21, 1937. [Classes 40 (iii) and 40 (v)] [Also in Groups XI and XXXVII] An electric lamp bulb 11, Fig. 1, containing the filament 12 is automatically adjusted in relation to a base collar 14 by means of a photo-electric cell 28 on which a beam of light is thrown from the filament, the automatic adjustment bringing the filament to a position where the light thrown on the photo-cell is a maximum. The collar 14 is clamped in a support 15 by jaws 16, encircled by a spring 20. The jaws are opened out by a plunger 19 operated by a pedal when a collar is to be inserted or removed. The bulb 11 is placed in approximate position in the collar 14 and held by a suction cup 22 on an arm 33. The filament is fed with current through contacts 24, 25 ; and the eight from the filament thrown by a parabolic reflector 21 to a lens 29 which directs the light to the photo-cell 28. A screen 30 may be inserted between the lens and the cell to avoid interference by stray light. The cell 28 controls motors 37, 35, 31 in succession. The motor 37 adjusts the lamp along the optical axis; and the motors 36, 31 make adjustments in two directions at right-angles to each other transversely to the optical axis. The motor 31 drives through a reducing gear 40 a screw 39 which adjusts a block 32 carrying the arm 33. The motor 31 is carried by a block 34 adjusted by a screw and reducing gear by the motor 35, which is itself carried by a block 36 adjusted by screw and reducing gear by motor 37. When the lamp bulb has been inserted in approximate position and lighted, the operation of the motors is started by the temporary pressing of a push-button 41, Fig. 2. This connects a relay coil 42 across the mains 44, 47. The armature 48 of this relay 43 then holds the circuit of the coil 42 closed through wire 49, armature 50 of relay 51, and wire 45 ; and the armatures 53, 54 connect the windings of the motor 37 to wires 55, 56 leading to the reversing relay 57, thereby setting the motor in rotation. If this rotation causes an increase of illumination of cell 28, the relay 57 remains in its position ; but if the illumination of the cell decreases, the relay 57 reverses the connection to the motor 37 to cause the illumination to increase. The relay is operated by the thermionic valve 65. The grid of this valve is coupled by transformer 63 to an amplifier 61 fed by the cell 28; bias is given by a battery 66 ; filament is heated by secondary 72 of mains transformer 69 ; and anode is connected through relay 57 to secondary 68 of mains transformer. When the illumination of the cell reaches its maximum-and begins to decrease, a rapid change of voltage is applied through transformer 63, condenser 76 and leak 75 to grid of thermionic valve 74, which causes the temporary operation of relay coil 79 connected to anode of valve 74 and to mains transformer 69. The armature 80 then closes circuit of coil 84 of relay 51 through armature 81 of relay 51, armature 82 of relay 43, and wire 83. The armature 50 then breaks the holding- on circuit of coil 42 of relay 43 which resumes the position shown ; the circuit of coil 84 is held-on through armature 92 of relay 51 and armature 90 of relay 88 ; and the armatures 94, 95 connect the windings of the next motor 35 to the reversing relay 57. This motor in turn operates until the illumination of the cell is again brought to a maximum, when the relay coil 79 is again temporarily operated. This time, the armature 80 closes the circuit of the coil 97 of the third relay 88 through armature 81 of relay 51 and wire 96. The armature 90 then breaks the holding-on circuit of coil 84 of relay 51 which resumes the position shown ; armature 87 closes a holding-on circuit for coil 97; and armatures 99, 100 connect third motor 31 to reversing relay 57 for the third adjustment. When this is completed and relay coil 79 again temporarily operated, armature 80 closes circuit of coil 42 of relay 43, and the cycle of operations is repeated. After a desired number of cycles of operations or after a given length of time, a main switch (not shown) is turned' off, and the bulb 11 is fastened to the base collar 14. Specification 425,653, [Group XI], is referred to.